I'm not sure what caused it exactly, but I have my suspicions about a error that has been recently discussed in the forums. I saw this error myself, and thought nothing of it, but I want to ask to make sure.
I noticed I did get the new map, and all, and everything seemed OK at first, but when I got the Darkside/Northern Tales portions of the mod, I've noticed the areas never showed up despite the fact I was at the right position of the map for the traverse to happen. Then it hit me, I remember the worldmap had a install error, and I was wondering why the Icewind Dale portion was not showing up for the Drizzt Saga on the worldmap (not the areas, but the map itself),(it is my first time installing that mod, taking guesses here). Then I remembered about the Dark Horizon's mod strange errors, some characters had some weird dialogue after they died, and made me wonder if there was some kind of conflict with the AR-AreaCode because the area code for Peldvale was changed, and thus might have messed with Darkside, and somehow with Northern as well(Woods of the dead couldn't even be accessed). I don't think anyone I've read on the forum had a problem with the Darkside/Northern/Dark Horizons installed together (I don't think Drizzt Saga would affect it) as far I know.
I'm just taking shots in the dark here, but it could be that recent worldmap error for the previous BWS might have corrupted map locations. Again I'm not code-savvy, and I might be imagining it.
Either way, if it was the recent error that users like myself got from the worldmap-bgt recently...then I guess it's that, but if it's the mods themselves then that would mean there is a conflict I've found with the mods. Also of note I've noticed when I was in section Headquarters in Dark Horizons, the NPC named Quayle instantly dies in some unknown location when I was in the dark round area with a lone throne in the middle.